Women who are deficient in vitamin B before they conceive may be more likely to give birth to obese and hypertense babies, according to a study conducted on sheep by researchers from the University of Nottingham, England, and published in the journal Proceedings of the National Academy of Sciences.

Researchers fed 25 female sheep a balanced diet, while depriving another 25 of sufficient B vitamins to induce deficiency. The deficient sheep were kept in that state for eight weeks before being artificially inseminated, and for the next six days as well. After six days, the embryos from the vitamin B-deficient sheep were transferred to sheep that had been fed a balanced diet.

The embryos from the eggs of B-deficient sheep were significantly more likely to be obese and to experience high blood pressure in adulthood, and the effect was particularly pronounced in males.

The males conceived by vitamin B-deficient mothers were 25 percent fatter than the male sheep born to well-nourished females. The study found no effect of vitamin B deficiency on the chance of conception or the birth weight of the lambs. "This modest early dietary intervention led to adult offspring that were both heavier and fatter, elicited altered immune responses to antigenic challenge, were insulin-resistant, and had elevated blood pressure - effects that were most obvious in males," said lead author Kevin Sinclair.

Prior research in humans has indicated that women who are deficient in folate (a form of vitamin B-9) during the first 28 days of pregnancy, before signs of pregnancy usually appear, are significantly more likely to bear children who have spinal bifida and ancephaly. Supplementation with folate or folic acid after this time period will have no effect on a child that has already developed a neural tube defect.

A study earlier in 2007 showed that high blood levels of vitamin B-6 before conception may decrease the risk of miscarriage during early pregnancy.